Systems and methods for a uniform gas flow in a separation chamber

Abstract

Device for controlling the gas flow in a deposition chamber (100), the device comprising: an inner wall (306; 406), wherein the inner wall (306; 406) forms a receiving section that receives a wafer support structure (134); an outer wall (304; 404) arranged opposite the inner wall (306; 406); and a top surface (302; 402) coupled to both the inner wall (306; 406) and the outer wall (304; 404), wherein the top surface (302; 402) is supported by the inner wall (306; 406) and the outer wall (304; 404), thereby keeping the top surface (302; 402) separated from a bottom of a chamber housing (102) of the deposition chamber (100) when the device is positioned within the chamber housing (102) of the deposition chamber (100); wherein several openings (310, 312; 410, 412) extend through the top surface (302; 402), the several openings (310, 312; 410, 412) being configured to allow a gas flow (140;240) to distribute the gas coming from above the device when the device is positioned above a gas outlet port (106) of the deposition chamber (100); wherein at least two of the multiple openings (410, 412) have different dimensions; or wherein a number of openings (310, 312) on one side of the top (302) is larger than the one opposite the gas outlet port (106).;

Description

BACKGROUND The integrated semiconductor circuit industry has experienced tremendous growth in recent decades. Technological advances in semiconductor materials and design have led to increasingly smaller and more complex circuits. These advances in materials and design were made possible by the technological progress made in processing and manufacturing. As semiconductor development progressed, the number of interconnected components per unit area has increased in direct proportion to the decrease in the size of the smallest component that can be reliably manufactured. Another trend in the industry is the increase in the diameter of the substrates on which semiconductor devices are built. Over the years, the industry has seen transitions from 100 to 200 millimeters, from 200 to 300 millimeters, and now from 300 to 450 millimeters. As the substrates have become larger, it has become more difficult to form uniform layers of material on a wafer. The currently existing deposition chambers have proven less than ideal for producing such layers. From US 2013 / 0 206 066 A1, a deposition chamber with a cover element is known which includes a plurality of openings that are uniformly and symmetrically distributed and have the same size. US 2009 / 0218043A1 describes the use of a leveling plate in a deposition chamber, wherein the leveling plate has a plurality of openings and is supported by a wafer carrier onto which a wafer can be placed. SUMMARY OF THE INVENTION The present invention relates to a device for controlling the gas flow in a deposition chamber according to claim 1, a deposition chamber according to claim 9, and a method for depositing a material uniformly over a substrate according to claim 15. Preferred embodiments of the invention are specified in the dependent claims. BRIEF DESCRIPTION OF THE DRAWINGS Aspects of the present disclosure are better understood with reference to the accompanying figures. It should be noted that, in accordance with common industry practice, various features are not drawn to scale. Rather, the dimensions of the various features may be enlarged or reduced as desired to facilitate understanding of the discussion. Fig. 1A is a partial cross-sectional view of a deposition chamber that is not according to the claim. Fig. 1B is another cross-sectional view of the entire deposition chamber illustrated in Fig. 1A. Fig. 2A is a partial cross-sectional view of a deposition chamber according to aspects of the present disclosure that are not according to the claim. Fig. 2B is another cross-sectional view of the entire deposition chamber illustrated in Fig. 2A.Figure 3A is a partially cross-sectional diagram of a further deposition chamber according to aspects of the invention as defined by the claims. Figure 3B is a further cross-sectional diagram of the entire deposition chamber illustrated in Figure 3A. Figure 4A is a partially cross-sectional diagram of a further deposition chamber according to aspects of the invention as defined by the claims. Figure 4B is a further cross-sectional diagram of the entire deposition chamber illustrated in Figure 4A. Figure 5 is a flowchart of a method for depositing material uniformly over a substrate according to aspects of the present disclosure that are not claimed. Aspects of this revelation can best be understood by referring to the accompanying figures and the following detailed description. DETAILED DESCRIPTION The following disclosure provides many different embodiments or examples for implementing various features of the disclosure. Specific examples of components and arrangements are described below to simplify the present disclosure. Furthermore, the present disclosure may repeat reference numbers and / or letters in the various examples. This repetition serves the purpose of simplicity and clarity and does not in itself indicate a relationship between the various embodiments and / or configurations discussed. Furthermore, spatially relative terms, such as "below," "under," "lower," "above," "upper," and the like, can be used in this text to simplify the description and to describe the relationship of an element or feature to one or more other elements or features, as illustrated in the figures. These spatially relative terms are intended to encompass various orientations of the component in use or operation, in addition to the orientation shown in the figures. For example, if the component in the figures is reversed, elements described as "below" or "underneath" other elements or features would then be oriented "above" them. Thus, the exemplary term "below" can encompass both an orientation above and below.The device may also be oriented differently (rotated by 90 degrees, or in other orientations), and the spatially relative descriptors used in the present text may also be interpreted accordingly. Let us now turn to Fig. 1, which illustrates a partial cross-section of a deposition chamber 100. The deposition chamber 100 is a material deposition chamber for depositing material layers onto a substrate during the fabrication of a semiconductor device wafer and can be used to deposit layers using techniques such as chemical vapor deposition (CVD), physical vapor deposition (PVD), and other deposition methods, whereby a gas is passed over one or more substrates. In Fig. 1, a chamber housing 102, which defines a chamber volume 104, and a pump port 106 are shown in cross-section. The chamber housing 102 is illustrated in a size suitable for a single wafer. However, some embodiments of the chamber housing 102 can be large enough to accommodate many wafers during a deposition process.The chamber housing 102 contains one or more wafer inlets and outlets (not shown) to allow the insertion and removal of wafers from the chamber volume 104. Alternatively, the chamber housing 102 can contain removable sections that can be detached for inserting and removing wafers and can be attached to one another during operation. The pump port 106 is a gas outlet port (and may be referred to as an outlet port 106 in this text) used to withdraw one or more gases that were introduced into the chamber volume 104 during the separation process. A pump (not shown) can be coupled to the outlet port 106 to generate a lower pressure at the outlet port and thus assist a gas flow through the chamber volume 104. Fig. 1 further illustrates several features of the separation chamber 100, which are not shown in cross-section but instead in a corresponding side view. A shower head 110 is provided as a gas flow source in an upper section of the chamber volume 104 and includes a gas supply line 112 and a flow distributor 114. The gas supply line 112 can be coupled to pressurized gas sources to allow the precursor gas to flow into the chamber housing 102. In embodiments where the gas flow source is located in the upper section of the chamber volume 104, gravity can assist the distribution and flow of the gas through the chamber volume 104. A pressure differential at the shower head 110 and at the outlet port 106 also ensures the flow of gas through the chamber volume 104. When a precursor gas enters the chamber volume 104 from the flow distributor 114, it flows onto a substrate 120, which is positioned and supported by a wafer carrier 130. The wafer carrier 130 includes a wafer table 132 and a wafer support structure 134, which holds the wafer table 132 above the bottom of the chamber volume 104. As illustrated in Fig. 1A, the wafer carrier 130 supports a single substrate 120. However, in some embodiments, more than one substrate is supported on the wafer carrier 130 during a deposition process. The wafer carrier 130 can include several features that can be used during a deposition process. The wafer table 132 can include a heater and a temperature sensor to control and / or monitor the temperature of the substrate 120, and can include a vacuum system to hold the substrate 120 in position during deposition.The wafer support structure 134 can supply the wafer table 132 with electricity and a vacuum and can also change the position of the wafer table 132 and thus of the substrate 120 in a controlled manner. For example, the wafer support structure 134 can be coupled with motors and servos to raise, lower and / or rotate the wafer table 132. Fig. 1B shows a cross-sectional view along line B1-B1 of Fig. 1A. Similarly, Fig. 1A is partially cross-sectional along line A1-A1 of Fig. 1B. Fig. 1B illustrates that the outlet port 106 is configured off-center, or offset from the center of the bottom of the chamber housing 102. Furthermore, a hollow interior 136 of the wafer support structure 134 is shown. Electricity and vacuum or low pressure can be supplied to the wafer table 132 through the hollow interior 136 of the wafer support structure 134. We return to Fig. 1A. This figure contains several arrows drawn with dashed lines to illustrate a gas flow 140. The gas flow 140 represents the path of a flow of gas at different positions within the chamber volume 104 over a period of time. The gas flow 140 can be a stream of gaseous hexachlorosilane (HCD or Si₂Cl₆), dichlorosilane (DCS or SiH₂Cl₂), bis-(tert-butylamino)silane (BTBAS or C₈H₂₂N₂Si), disilane (DS or Si₂H₆), or another PVD or CVD precursor gas. The gas flow 140 of Fig. 1A shows that gas on one side of the chamber housing 102, which contains the outlet port 106, so that the gas is closer to this point, can flow faster than gas introduced through the shower head 110 on one side opposite the outlet port 106.Because the gas flow rates illustrated by the gas flow 140 are not uniform, a layer of material deposited on the substrate 120 (or the multiple substrates) may also not be uniform. The faster flow on the outlet port side of the chamber volume 104 may result in a thinner or thicker layer of deposited material on one side of the substrate 120 than on the other. As the size of a given substrate 120 increases, the variations in the resulting material layer may become more significant. Figures 2A and 2B illustrate the deposition chamber 100 with an outlet port cover 200 positioned within the chamber housing 102 and above the outlet port 106. Figure 2B is a cross-sectional view along line B2-B2 of Figure 2A. Similarly, Figure 2A is a partial cross-sectional view along line A2-A2 of Figure 2B. The outlet port cover 200 includes a top surface 202, which is supported by an outer wall 204 and separated by this wall from a bottom surface of the chamber housing 102. The illustrated configuration further includes an inner wall 206 opposite the outer wall 204. As illustrated, the inner wall 206 has a cylindrical shape that accommodates the cylindrical cross-section of the wafer support structure 134. In Figures 2A and 2B, the inner wall 206 is shown in Figure 2A.2B there is a separation distance between the inner wall 206 and the wafer support structure 134, but in some embodiments the inner wall 206 or a section thereof is directly adjacent to the wafer support structure 134. The outlet port cover 200 can be installed during the assembly of the deposition chamber 100 or can be retrofitted to an existing deposition chamber by removing and then reinstalling the wafer table 132. The outlet port cover 200 can be permanently attached to the bottom of the chamber housing 102, for example by bolting or welding, or it can be positioned within it in a removable manner. Furthermore, the top surface 202 can be planar or contoured to promote gas flow uniformity. The top surface 202 and the outer and inner walls 204 and 206 of the outlet port cover 200 define an interior space 208 accessible through several openings or holes. Two of the multiple openings are illustrated in the cross-sectional view of the outlet port cover 200 in Fig. 2A: a near opening 210 and a distant opening 212. The near opening 210 is closer to the outlet port 106 than the distant opening 212. As can be seen in Fig. 2B, the top surface 202 contains a total of 8 openings, such as openings 210 and 212. The openings are illustrated as circular, but in some embodiments the openings may also be triangular, oval, square, or otherwise shaped. Some embodiments include openings of various shapes. The multiple openings are arranged symmetrically relative to a center point of the top surface 202, which is shown in Fig.2B is illustrated as being ring-shaped, but in other embodiments it can generally be rectangular or otherwise shaped. The outlet port cover 200 regulates the gas flow from the shower head 110 to the outlet port 106 so that it is more uniform. Thus, a gas flow 240 can be more uniform than the gas flow 140 shown in Fig. 1A. By regulating the gas flow so that it is more uniform across the wafer 120, the outlet port cover 200 can promote the deposition of more uniform material layers. The greater uniformity of the deposited material layers can result in semiconductor devices with higher production yield and improved performance. Figures 3A and 3B illustrate the deposition chamber 100 with an outlet port cover 300 positioned within the chamber housing 102. Figure 3B is a cross-sectional view along line B3-B3 of Figure 3A, which is a partial cross-section along line A3-A3 in Figure 3B. The outlet port cover 300 has many of the features described above in connection with the outlet port cover 200 of Figures 2A and 2B. For example, the outlet port cover 300 includes a top surface 302, an outer wall 304, and an inner wall 306, which accommodates the wafer support structure 134. The outlet port cover 300 and the chamber housing 102 define an interior space 308, which is directly accessible through several openings and the outlet port 106. In contrast to the outlet port cover 200, the outlet port cover 300 contains several asymmetrically arranged openings. As shown in Fig. 3A, the top surface 302 has a single near opening 310 and two distant openings 312A and 312B. As shown in Fig. 3B, the multiple openings are arranged asymmetrically with respect to the wafer support structure 134, but symmetrically with respect to an imaginary line between the outlet port 106 and the support structure 134. In some embodiments, the multiple openings in the top surface 302 need not exhibit any symmetries, but can be completely asymmetrical. As shown in Fig. 3B, there are fewer openings on the near side of the outlet port cover 300 than on the far side. In the illustrated embodiment, all openings have identical geometries. Thus, the outlet port cover 300 has more open area on the far side than on the near side. This can improve the uniformity of the gas flow 340, as shown in Fig. 3A. The larger open area provided by the more numerous openings on the far side of the outlet port cover 300 can counteract an effect caused by the proximity of the openings on the near side to the outlet port 106. That is, although the gas flow within the interior 308 may not be uniform, the gas flow 340 over the top 302 may be more uniform. Figures 4A and 4B illustrate the deposition chamber 100 with an outlet port cover 400 positioned within the chamber volume 104. Figure 4B is a cross-sectional view along line B4-B4 of Figure 4A, which is a partial cross-section along line A4-A4 in Figure 4B. The outlet port cover 400 may share many features and properties with the outlet port covers 200 and 300 of Figures 2A and 2B and Figures 3A and 3B. The outlet port 400 has a top surface 402 with several openings passing through it. The top surface 402 is coupled to and supported by an outer wall 404 and an inner wall 406, thus offsetting the top surface 402 from the bottom of the chamber housing 102. Together, the outlet port cover 400 and the chamber housing 102 form an interior space 408. As can be seen in Fig. 4A, the multiple openings include a near opening 410 and a far opening 412.The near opening 410 has a smaller diameter than the far opening 412, and the diameter of the multiple openings increases as the distance from the outlet port 106 increases, as shown in Fig. 4B. This creates a larger open area on a far side of the top surface 402 than on a near side, which can counteract a faster flow due to the proximity of the openings on the near side to the outlet port 106, thus promoting a more uniform gas flow 440, as illustrated in Fig. 4A. This greater uniformity can result in higher quality, excellent-performing semiconductor devices and a higher production yield. Combinations of the various features of the outlet port covers 200, 300, and 400 are within the scope of protection of this disclosure. In some embodiments of outlet port covers, a top surface may have openings comprising approximately 20 to approximately 80 percent of the total area of ​​that top surface. The combined area of ​​the openings on a top surface may range from approximately 20 square centimeters to approximately 1400 square centimeters. The openings may be symmetrical with respect to certain features of a deposition chamber, or they may be asymmetrical. The top surface may be planar, convex, or concave, or may be a combination of such surfaces. The outlet port covers may be made of a ceramic material or a metal, such as stainless steel, that can withstand the high temperatures that may occur during CVD, PVD, or other deposition processes involving gas flow.The outlet port covers described above can improve the uniformity of gas flow across one or more substrates on which a material layer deposition process is performed. This can lead to advantages in production yield and component quality. Fig. 5 is a flowchart of a method 500 for depositing a material uniformly over a substrate. The method 500 includes several numbered steps, as illustrated in Fig. 5, but embodiments of the method 500 may include further steps before, after, and between the numbered steps. Thus, the method 500 may begin in step 502, where a substrate is placed in a deposition chamber and positioned below a gas flow source and above a gas outlet port. The gas outlet port is located off-center within the deposition chamber. Such a deposition chamber is illustrated in Fig. 2A and Fig. 2B, where the deposition chamber 100 has the shower head 110 and the outlet port 106. In step 504, gas is passed through the gas flow source over the substrate, with at least a portion of the gas flowing below the substrate. As shown in Fig.As shown in Figure 2A, a gas entering the chamber volume 104 through the shower head 110 flows downward over the substrate 120, where some of the gas reacts to deposit a layer of material. Alternatively, the gas may react above the surface of the substrate 120, causing the reacted material to be deposited downward onto the substrate 120. At least some of this gas and / or byproduct gases generated in the reaction with the precursor gas flows below the substrate 120. In step 506, this flowing gas is directed through multiple openings in an outlet port cover to the gas outlet port. The multiple openings are configured to treat, regulate, or direct the gas flowing from the gas flow source and through the multiple openings so that it flows through the top of the outlet port cover in a substantially uniform manner.For example, the outlet port covers 200, 300 or 400, as described above, can direct the gas so that it flows more evenly from the shower head 110 over the substrate 120.

Claims

Device for controlling the gas flow in a deposition chamber (100), the device comprising: an inner wall (306; 406), wherein the inner wall (306; 406) forms a receiving section that receives a wafer support structure (134); an outer wall (304; 404) arranged opposite the inner wall (306; 406); and a top surface (302; 402) coupled to both the inner wall (306; 406) and the outer wall (304; 404), wherein the top surface (302; 402) is supported by the inner wall (306; 406) and the outer wall (304; 404), thereby keeping the top surface (302; 402) separated from a bottom of a chamber housing (102) of the deposition chamber (100) when the device is positioned within the chamber housing (102) of the deposition chamber (100); wherein several openings (310, 312; 410, 412) extend through the top surface (302; 402), the several openings (310, 312; 410, 412) being configured to allow a gas flow (140;240) to distribute the gas coming from above the device when the device is positioned above a gas outlet port (106) of the deposition chamber (100); wherein at least two of the multiple openings (410, 412) have different dimensions; or wherein a number of openings (310, 312) on one side of the top (302) are larger than those opposite the gas outlet port (106).; Device according to claim 1, wherein the inner wall (306; 406) is the same height as the outer wall (304; 404). Device according to claim 1, wherein the receiving section contacts the wafer support structure (134). Device according to claim 1, wherein the multiple openings (410; 412) are symmetrically distributed on the top surface (402). Device according to claim 1, wherein the multiple openings (310, 312A, 312B; 410, 412) comprise openings (310; 410) on a near side of the top (302; 402) and openings (312A, 312B; 412) on a far side of the top (302; 402), the near side being closer to the gas outlet port (106) than the far side, and wherein the openings (312A, 312B; 412) on the far side of the top (302; 402) form a larger combined open area than the openings (310; 410) on the near side of the top (302; 402). Device according to claim 1, wherein a combined open area formed by the multiple openings (310, 312; 410, 412) lies in a range of about 20 percent to about 80 percent of a total area of ​​the top surface (302; 402). Device according to claim 6, wherein the combined open area is in a range of 0.25 square centimeters to 100 square centimeters. Device according to claim 1, wherein at least some openings (310, 312; 410, 412) of the multiple openings (310, 312; 410, 412) are non-circular. Deposition chamber (100) comprising: a chamber housing (102); a gas flow source (110) arranged in an upper region of the chamber housing (102); a gas outlet port (106) positioned on a bottom of the chamber housing (102) and offset from a center of the bottom; a wafer carrier (130) configured to position a wafer (120) below the gas flow source (110); and an outlet port cover (400) having a top (402) through which several openings (410, 412) pass, configured to control a gas flow (140) from the gas flow source (110) to the gas outlet port (106), the outlet port cover (400) being located on the bottom of the chamber housing (102) and being permanently or removably attached thereto;wherein the multiple openings (410, 412) include openings (410) on a near side of the top surface (402) and openings (412) on a far side of the top surface (402), the near side being closer to the gas outlet port (106) than the far side, and wherein the openings (412) on the far side of the top surface (402) form a larger combined open area than the openings (410) on the near side of the top surface (402). Deposition chamber (100) according to claim 9, wherein the wafer carrier (130) comprises a wafer table (132) and a wafer support structure (134), wherein the wafer support structure (134) is centered within the chamber housing (102), and wherein a receiving hole (136) extends through the outlet port cover (200; 300; 400) through which the wafer support structure (134) passes. Deposition chamber (100) according to claim 9, wherein the multiple openings (410, 412) in the top (402) of the outlet port cover (400) are distributed symmetrically around a center of the top (402). Deposition chamber (100) according to claim 9, wherein the upper surface (402) is annular. Deposition chamber (100) according to claim 9, wherein the outlet port cover (400) is made of a ceramic material or metal. Deposition chamber (100) according to claim 9, which is configured as a chamber for material deposition by chemical evaporation or physical evaporation. A method for depositing a material uniformly over a substrate (120), the method comprising: positioning a substrate (120) below a gas flow source (110) and above a gas outlet port (106) in a deposition chamber (100), the gas outlet port (106) being arranged off-center below the gas flow source (110), the substrate (120) being positioned on a wafer carrier (130), the wafer carrier comprising a wafer table (132) and a wafer support structure (134), the wafer table (132) supporting the substrate and the wafer support structure (134) holding the wafer table (132) above a bottom of a chamber housing (102) of the deposition chamber (100); directing gas from the gas flow source (110) over the substrate (120), at least a portion of the gas flowing below the substrate (120); and directing the gas flowing below the substrate (120) to the gas outlet port (106) through several openings (310, 312;410, 412), which are formed in a top surface (302; 402) of an outlet port cover (300; 400), wherein the outlet port cover (300; 400) is located on the bottom of the chamber housing (102) and the top surface (302; 402) is located below the wafer table (132), wherein: - at least two openings of the multiple openings (410, 412) have different dimensions; or - a number of openings (310, 312) on one side of the top surface (302) is larger than opposite the gas outlet port (106); or- the multiple openings (310, 312A, 312B; 410, 412) include openings (310; 410) on a near side of the top (302; 402) and openings (312A, 312B; 412) on a far side of the top (302; 402), wherein the near side is closer to the gas outlet port (106) than the far side, and wherein the openings (312A, 312B; 412) on the far side of the top (302; 402) form a larger combined open area than the openings (310;410) on the near side of the top (302; 402); such that the multiple openings (210, 212; 310, 312; 410, 412) are configured to cause the gas flowing between the gas flow source (110) and the multiple openings (310, 312; 410, 412) to flow uniformly over the outlet port cover (300; 400).; The method according to claim 15, which further comprises introducing the substrate (120) into a deposition chamber (100). Method according to claim 15, wherein the outlet port cover (200; 300; 400) contains the multiple openings (210, 212; 310, 312; 410, 412) arranged in an annular area.

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